There have been disclosed related techniques regarding image analyzing apparatuses and systems for performing analyses effective for making diagnoses of pathologic tissue images through executing computer processing on digitized pathologic tissue images.
For example, there is considered a method which includes a module that detects ducts and a duct area constituted with a plurality of different ducts within a pathologic tissue image based on a closed area surrounded by a cell-nucleus area and a module that detects the ducts based on the number of the cell-nucleuses within a specific width of the periphery of the duct area, and performs an analysis of the pathologic tissue image by evaluating the uniformity of the sizes as well as the shapes of the nucleuses of the cell-nucleuses contained in the ducts detected by those modules and the abnormality in the polarities.
Among the pathologic tissue images, high differentiated adenocarcinoma observed particularly in a colonic biopsy includes many meandering ducts and most of shapes thereof are far from a substantially circular shape. Further, it is also characterized to have a large number of swollen vacant nucleuses.
Further, pseudo-stratification of the cell-nucleuses in the duct area is conspicuous. Thus, the stratification parts of the cell-nucleuses are not arranged on the base side and distributed irregularly, and this tendency is prominent.
Therefore, it is not possible with the above-described method to extract the area as a closed area surrounded by the cell-nucleus area when the cell-nucleuses are not arranged in an orderly manner or when there are vacant cell-nucleuses. Further, also when detecting a duct based on a gland lumen area, it is not possible to extract the area when the gland lumen area is not closed.
Further, when a plurality of cell-nucleuses forming the duct are connected, it is difficult to discriminate each one of the cell-nucleuses separately even if a high-magnification image is used. Furthermore, the vacant cell-nucleus is shown in white on the image, so that the vacant cell-nucleus cannot be recognized as a nucleus. Therefore, it is not possible to precisely evaluate the uniformity of the sizes as well as the shapes of the cell-nucleuses contained in the ducts and the abnormality in the polarities.
As a related technique thereof, there is disclosed a system which acquires distribution information of cell-nucleuses and cytoplasm contained in a pathologic image based on a NC ratio (area of nucleuses within a cell area of cytoplasm within a cell) which shows the proportion of the area of the cytoplasm occupying the cell with respect to the area of the cell-nucleuses within the cell in a tissue image in a quantitative manner, and determines the distribution of a cancer part and the progression degree of the cancer based on the information (Patent Document 1). This method is particularly considered effective in the prostate cancer diagnoses.
Further, as a related technique thereof, there is disclosed a method which selects a gland lumen based on luminance information, sets a contour of the gland lumen within an image, acquires a frequency distribution of a dark purple color on an equidistant curve from the gland lumen, discriminates the ducts by distinguishing the ducts from blood vessels by observing the peak positions, and analyzes the concentric structure (particularly the structure of the prostate) contained in the pathologic image (Patent Document 2).
Furthermore, as a related technique thereof, there is disclosed a method which extracts construction information of cell-nucleuses by using image processing and searches past similar case images by using it as a characteristic amount (similar image searching) to make it possible to support doctors' diagnoses (Patent Document 3). This method is particularly considered effective in the stomach biopsy diagnoses.
In order to extract the construction information of the cell-nucleuses, this related technique first acquires a threshold value by using a discrimination/analysis method according to luminance components for separating the cell-nucleus areas, and detects cell-nucleus construction area by slightly shifting the threshold value.
Then, this related technique provides a similarity searching method which uses the area content rate showing the rate of the cell-nucleus construction areas occupying the area of the cytoplasm and the average area of the cell-nucleus construction areas as cell-nucleus construction characteristic amounts. The cell-nucleus construction area shows the duct area.    Patent Document 1: Japanese Unexamined Patent Publication 2004-286666    Patent Document 2: Japanese Unexamined Patent Publication 2005-352571    Patent Document 3: Japanese Unexamined Patent Publication 2009-9290
However, the related technique disclosed in Patent Document 1 is a diagnosis using the NC ratio, and it simply compares the area of the cell-nucleuses and the area of the cytoplasm contained in a specific area within an image in a comprehensive manner but does not evaluate the arrangement of each of the cell-nucleuses.
Thus, the characteristics of cancer cells that can be measured based on the NC ratio are limited only to swelling of the nucleuses and the like. Therefore, the information of the NC ratio is insufficient for evaluating the ducts so that evaluations cannot be done accurately.
Further, while the related technique disclosed in Patent Document 2 can be adapted to discriminating the ducts from the blood vessels, evaluations are done by exceeding the boundary of the duct area on an equidistant curve because of the thickness of the ducts when evaluating formation of the ducts.
Furthermore, this is a method which is employed on assumption that the gland lumen is a closed area and the equidistant line is a closed curve. Therefore, it cannot be employed to a case that includes a protruded structure such as an actual duct and a looped and filled structure and to a case where the gland lumen is not a closed area.
Moreover, with the technique disclosed in Patent Document 3, a lymphocyte of high luminance colored in dark blue is mis-detected as a duct area in the discriminating analysis of luminance components.
Further, with the technique disclosed in Patent Document 3, goblet cells existing within the duct area colored in a light color by Hematoxylin-Eosin stain (HE) are handled as a background area. Thus, detection of the duct areas becomes inaccurate.
Furthermore, the amount for characterizing the duct is a ratio, and it is insufficient to evaluate the duct by a primary statistic only with the ratio.
An object of the present invention is to provide a pathologic tissue image analyzing apparatus, a pathologic tissue image analyzing program, and a pathologic tissue image analyzing program, which can effectively improve the differentiation accuracy of cancers in pathologic diagnoses done by performing pathologic tissue image analyses.